Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$172.97	13.649%	$196.5787	$196.58	$196.60	$196.60
Purchase #2	$171.42	9.148%	$187.1015	$187.10	$187.10	$187.10
Purchase #3	$34.41	10.583%	$38.0516	$38.05	$38.05	$38.10
Purchase #4	$182.84	12.624%	$205.9217	$205.92	$205.90	$205.90
Purchase #5	$144.31	11.296%	$160.6113	$160.61	$160.60	$160.60
Purchase #6	$72.46	5.180%	$76.2134	$76.21	$76.20	$76.20
Purchase #7	$232.79	11.648%	$259.9054	$259.91	$259.90	$259.90
7 purchase totals =	$1,011.20		$1,124.3836	$1,124.38	$1,124.35	$1,124.40